Storage battery



Patented July 5, 1927.

UNITED,

1,634,527 PATENT OFFICE".

' "WILLIAM s.- woon, or'soUTH EUCLID, omo.

STORAGE BATTERY.

.No Drawing. 7

This invention relates to storage batteries and has forits objects the provision of a lead type battery of decreased internal resistance thereby producing a higher dischargerate tuting a part of an assembled battery. Other objects and advantages of the invention will become apparent as the description proceeds.

Accumulators of the lead type as employed for vehicle use consist of spaced positiveand negative plates and thin wooden separators between them. Nearly everykind of wood has at different times been employed for this purpose, the preferred species at the present time being generally cedar, redwood, and quarter-sawed oak, Many of these are treated with lye to remove the resinous and acid portions which inight be deleterious to the battery elements. This treatment, however, leaves the cellulose intact, indeed it has to some extent the effect of mercerizing it, with the result that upon the slightest drying the cellulose fibers contract and close up the pores in such -a Way as greatly to injure the performance of any battery made therefrom. 7

According to my invention a part of this cellulose is removed by the action of sulphuric acid of the proper strength. The strength of the acid and the duration of treatment thereby depends upon the species of the wood and the previous treatment if any to which it has been subjected. If separators are used which have already been treated with lye, a weaker acid, and. a shorter time of treatment are required because the alkali treatment has already removed a considerable part of the resinous-substances so that the acid can get more immediate action on the cellulose. As an example of a beneficial treatmentI instance soaking for fifteen minutes in a solution of sulphuric acid in water of a specific quantity of 1.400. In case of quarter sawed oak I instance as a good treatment the immersion for one-half hour in a similar solution. This treatment is also beneficial to othertypes of wood which do Application filed Qctober15, 1924. Serial No. 743,844.

not ordinarily make very good separators such as plain-sawed .oak and other hard Woods. Of course the time of treatmentalso depends upon the strength of, the acidand the temperature, and I do not limit myself in either respect although I have discovered that 1.300 is too low and 1.500 is too high for practicalproduction conditions.

If the separators are taken from this acid treatment and; assembled immediately. in the final battery its discharge rate and available voltage are substantially increased. In case it is impossible to assemble the separators immediately in a battery, as is usually the case under large scale production conditions, itis necessaryto observe certain precautions to avoid injury by continued action of the acid, which action may evenbe-intensified by concentration due to evaporation. Mere rinsing in water is sufficient for a delay of a few minutes but not for any long interval since the acidin the pores'cannot be wholly removed in this manner, and upon evaporation Willbecome s0 concentrated as in time to injure the material. If kept submerged in water (orra weaker sulphuric acid solution) these treated separators can be kept indefinitely. l 7

However, it is possibleby immersing these separators in a hot concentrated solution of Epsom salts to render the separators immune to drying and to the evils of shrinkage or undue corrosion. Prior to immersion these separators ought to be rinsed with water to an extent sufiicient at least to remove the,

adherent acid. The concentration and temperature of the solution can vary considerably, but I prefer such conditions that the separators will be sensibly dry as soon as they reach air temperature, although I do not limit myself even to this as I have had excellent results by the use of cold solutions. 1

It is only necessary to leave the separators in the solution until theyare thoroughly impregnated, but the stronger the solution the quicker the separator will become dry after removal.

It is of course possible to remove the suldehyde, etc., but even in-this case it is very I advantageous to employ the .Epsom salt treatment in order to prevent the shrinkage and loss of porosity which would otherwise occur. Removal of the acid is not necessary, however, in case of the Epsom salt treatment.

I do not restrict myself to; the treatment of separators wherein cellulose occurs naturally, as I have found it valuable in con: nection with devices of this character wherein the cellulose is introduced artificially, as

by embedding cotton, sawdust, etc. in a matrix of rubber. The presenceot Epsom salts is not injurious to a lead accun'mlator' and it is not necessary to wash or soak the separators or othei w-ise cleanse them bei'ore assembling 1n battery form 111 case the separators are treated and used at ditlerent described my invention what 1.500 untilsu-liicient cellulose is removed therefrom to increase the porosity sensibly, but. without disintegration of the organic structure and afterward reducing the concentration of the adherent acid.

2. The process'ot treating the wood separators of lead accumulators which contains the step of removingout of them a portion ottheir cellulose by treatment with sulphuric acid of specific gravity above 1.300.

3. The process of treating the separators of lead accumulators which contains the step of immersing them in; sulphuric acid of a specific gravity above 1.300 and below 1.500 until sufiicientcellulose is removed therefrom to, increase the porosity sensibly, and afterward immersing in a strong solution of Epsom salts.

l. The process of treating the wood separa'tors ofnlead. accun'iulators which contains the step of removing out of them a portion of thin celluloseby treatment with sulphuric acid of specific gravity above 1.300 and afterward im a're natin with E osom' salts.

'S A separator for storage batteries consisting essentially of a thin plate rendered porous by the presence 01'; organized cell-ulose, the pores of the plate being filled with sulphur c acid, water, and Epsom salts.

6. separator element for storage batteries consisting of a sheet o tporous wood impregnated with sulphuric acid and mag-' n rum sulphate V 7. The process of arresting the corrosive action of: sulphuric acid on the elements of a storage battery which consists of washing oil the externally adherent acid and soaking the element in a strong solution of magnesium sulphate.

8. The process 0t improving theporosity 01? a battery separator containing organized ellulose which contains thesteps of first removing a part of the cellulose with a strong solution of sulphuric acid, and then arr stingthe action of the sulphuric acid with a strong solution of Epsom salts.

In testimony whereof, I hereuntoaflir; my I signature.

WILLIAM H. woon. 

